How to compile c file with OpenSSL includes

Question

I am trying to compile a small  c file that has the following includes    include  lt openssl ssl h gt   include  lt openssl rsa h gt   include  lt openssl x509 h gt   include  lt openssl evp h gt    In the same folder where i have the  c file I have a  openssl with all those files  and more   also in synaptic package manager I see OpenSSL installed  I am trying to compile with this   gcc -o Opentest Opentest c -lcrypto   but I always get the errors   error  openssl ssl h  No such file or directory error  openssl rsa h  No such file or directory error  openssl x509 h  No such file or directory error  openssl evp h  No such file or directory   The file I want to compile is only a  c file  doesnt have Makefile or   configure   I already tried   env CFLAGS -I path to openssl    and tried to compile again but i get the same errors   What should I do in order to compile with openssl includes

User · Answer

If the OpenSSL headers are in the openssl sub-directory of the current directory  use   gcc -I  -o Opentest Opentest c -lcrypto   The pre-processor looks to create a name such as    openssl ssl h  from the     in the -I option and the name specified in angle brackets   If you had specified the names in double quotes   include  openssl ssl h    you might never have needed to ask the question  the compiler on Unix usually searches for headers enclosed in double quotes in the current directory automatically  but it does not do so for headers enclosed in angle brackets   include  lt openssl ssl h gt     It is implementation defined behaviour   You don t say where the OpenSSL libraries are - you might need to add an appropriate option and argument to specify that  such as  -L  opt openssl lib

User · Answer

From the openssl pc file  prefix  usr exec prefix   prefix  libdir   exec prefix  lib includedir   prefix  include  Name  OpenSSL Description  Secure Sockets Layer and cryptography libraries and tools Version  0 9 8g Requires  Libs  -L  libdir  -lssl -lcrypto Libs private  -ldl -Wl -Bsymbolic-functions -lz Cflags  -I  includedir    You can note the Include directory path and the Libs path from this  Now your prefix for the include files  is  home username Programming    Hence your include file option should be -I  home username Programming     Yes i got it from the comments above   This is just to remove logs regarding the headers  You may as well provide -L lt Lib path gt  option for linking with the -lcrypto library

User · Answer

For this gcc error  you should reference to to the gcc document about Search Path   In short   1  If you use angle brackets  lt    with  include  gcc will search header file firstly from system path such as  usr local include and  usr include  etc   2  The path specified by -Ldir command-line option  will be searched before the default directories   3 If you use quotation     with  include as  include  file   the directory containing the current file will be searched firstly   so  the answer to your question is as following   1  If you want to use header files in your source code folder  replace  lt   with    in  include directive   2  if you want to use -I command line option  add it to your compile command line  if set CFLAGS in environment variables  It will not referenced automatically   3  About package configuration openssl pc   I do not think it will be referenced without explicitly declared in build configuration

User · Answer

Your include paths indicate that you should be compiling against the system s OpenSSL installation   You shouldn t have the  h files in your package directory - it should be picking them up from  usr include openssl   The plain OpenSSL package  libssl  doesn t include the  h files - you need to install the development package as well   This is named libssl-dev on Debian  Ubuntu and similar distributions  and libssl-devel on CentOS  Fedora  Red Hat and similar

User · Answer

Use the -I flag to gcc properly   gcc -I path to openssl  -o Opentest -lcrypto Opentest c  The -I should point to the directory containing the openssl folder

User · Answer

Use the snippet below as a solution for the cited challenge   yum install openssl yum install openssl-devel   Tested and proved effective on CentOS version 5 4 with keepalived version 1 2 7

User · Answer

You need to include the library path  -L usr local lib    gcc -o Opentest Opentest c -L usr local lib  -lssl -lcrypto  It works for me

[c] How to compile .c file with OpenSSL includes?

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